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Tuesday, 20 August 2013

The last technical plan required for HMS Terror is the upper deck, which I have finally completed.

Please note: This plan has been updated - please consult my later posts.

The original 1836 and 1839 deck plans for HMS Terror show the outlines of the ship with planking installed. Therefore, on my plans, I have included the outline of the frames as well as the planking to better facilitate construction. Like the original plans, the position of the solid chock channels accounts for tumblehome. Because the 1839 plans depict HMS Erebus, my plans are based on the 1836 upper deck plans for HMS Terror, but the deck furniture is the same type and style as drafted on the 1839 sheets (see previous posts for rationale). Similar to the profile plans, the position of the deck furniture is based on the 1836 sheets.
The most substantial modifications to the plans are at the stern - to accommodate the new position of the rudder and the well for the screw propeller. As a result, the central structure on the stern containing the cistern, color boxes, and water closet was removed from these plans (presumably these were moved to the position of one of the chicken coops). These modifications are also depicted in a contemporary image of the Erebus drawn by Owen Stanley, which shows two large structures on either side of the vessel at the stern.

The deck planking on the vessels was unusual and was not shown in any contemporary plans. Rice (Ross 1847), the shipwright responsible for the refitting, described them in detail:

A contemporary model of HMS Erebus displays that the upper layer of deck planking angled outwards and forwards from the central planks towards the bulwarks. This style was also used for the upper deck of HMS Investigator, which searched for the Franklin vessels on two voyages between 1848-1853. Investigator’s upper deck plan shows that the planking was placed on an angle about 45 degrees from the centerline. On my plans, the width of the central planks is based on the 1839 midships cross section, but the width of outer planks is not described in any contemporary sources and required more research. Fortunately, an archaeologist at the Canadian Museum of Civilization has recently identified a piece of 3 inch thick “fir” deck planking that she demonstrates is very likely to be from one of the vessels (if so it is the only piece of the ships known to currently exist). The plank is exactly 7 inches wide; therefore this is the dimension I use on my plans.
References:

Ross, Sir James Clark
1847 A Voyage of Discovery and Research in the Southern and Antarctic Regions, During the Years 1839-1843: Volume I. John Murray, London.

Tuesday, 13 August 2013

My
plans from the 1845 inboard profile of HMS Terror incorporate all of the
information presented in my previous post (as well as information to be
presented in subsequent posts). It represents nearly a year of research, and no
doubt contains unknown errors. Despite the fact that my model won’t show any
detail between decks (I intend to build a plank on bulkhead model), I felt the inboard
profile would be incomplete without these details.

Please note: This plan has been updated - please consult my later posts.

A
significant quantity of historic source material, including original Royal Navy
plans, exploration accounts, news reports, and personal letters, sketches, and
drawings exist which document the final 1845 configuration of HMS Terror.
Creating an accurate plan for the ship requires carefully parsing these data
and drawing inferences about the ship’s probable appearance. Below, I outline
the rationale behind my reconstruction of major aspects of the Terror’s final
1845 design, as fitted. This is not an exhaustive account, and specific topics
such as the locomotive engines, funnel and chimney sizes and positions,
propellers, cipher and name, and paint scheme will be discussed in later posts.

Bow/Stern
Shape:

As described previously, the 1839 plans depict
HMS Erebus, and therefore the 1836 profile must provide the basis for the
bow design of the Terror, which is substantially different from the 1813 profile.
It is uncertain if the 1836 refit resulted in modification of the cant frames,
but Rice (Ross 1847a) appears to indicate that bolsters were added to the
exterior of the frames to change the line of the bow.

In my plans, the stern configuration and
framing is exactly as depicted in the 1845 annotations (in green ink) of the
1836 profile, which were made to accommodate the auxiliary screw propeller.

Keel, False Keel, and Stem:

The
position and configuration of the keel is based on the 1813 inboard profile.
The stempost configuration is based in the 1836 inboard profile, but lengthened
slightly to accommodate the new position of the bowsprit as shown in the 1845
alterations (in green ink). I should note that a faint pencil modification in the
1813 inboard profile of HMS Vesuvius also appears to depict the outline of
the stempost as drawn in the 1836 Terror profile. The scarph joints on the
stempost are based on the 1813 profile, or based on standard designs for the era
(e.g. Goodwin 1987:29).

Keelson and Stemson:

The
keelson and stemson designs are based on the 1813 profile, but with alterations
at the stern to be consistent with the 1845 annotation (in green ink) of the 1836
inboard profile. The bolstering and riders added above the stemson are based on
the 1836 inboard profile plans.

Deadwood, Rising Wood, and Knee:

The
bow and stern deadwood configurations are not documented in any of the
Admiralty plans. Interestingly, the 1813 plans indicate that HMS Terror utilized
an older stemson design than the era in which it was built; therefore, the in
my plans the deadwood configuration is based on a style in use ca. 1800
(Goodwin 1987:29). The rising wood configuration at the bow is based on the
1813 profile which is partially complete, with information drawn from standard
styles utilized in the early 19th century (Goodwin 1987:29). The knee of the Terror was essentially removed (as
discussed by Rice [Ross 1847a]), and was replaced with a highly reduced and
simplified knee that projected only enough to support the bowsprit. The knee configuration
in my plans is based on the 1836 profile, lengthened to support the new
position of the bowsprit as depicted in the 1845 annotations on that plan. The
joints for the knee (i.e. the configuration of the gripe and bobstay pieces) are
based on standard conventions for the period (e.g. Goodwin 1987:37).

Rabbet Line:

Because
of the lengthening of the bow and the reduction in the knee, the Terror’s rabbet
line must have been highly unusual. The model of HMS Erebus at the National
Maritime Museum indicates that the knee (much of which was covered in plating)
was essentially flush with the hull planking at the bow.No rabbet is depicted in the 1836 plans of
the Terror, so at the bow I based in on the on the thickness of planking as
depicted in the 1839 midships section, with the goal of keeping the hull
planking below the chock channels (and excluding the wale) flush with the knee.
Closer to the keel, the rabbet line recedes until to meets the original rabbet
line depicted in the 1813 profile. The rabbet on the keel is based on the line depicted
in the 1813 profile.The rabbet at the
stern was easily deduced from the 1845 plan of the modified stern, which clearly
displays where the hull planking terminates.

Bow Plating:

The
position and size of the iron bow plating are based on the 1845 annotation (in
green ink) on the 1836 profile. This annotation indicates that iron plating was
more extensive than the cross-shaped copper plating used for the 1836 Back Expedition,
but did not extend along the waterline like the copper plating utilized for the
Antarctic Expedition (depicted in the 1839 profile).

Deck Fittings:

All
deck fittings for my plans are based on the 1839 inboard profile of the Terror
and Erebus (see a previous post for the discussion of the Royal Navy’s policy
of identically outfitting exploration vessels). As discussed previously, the
1839 plans depict the Erebus, so the positioning of the furniture, masts, and
other deck fittings are based on the 1836 Terror profile. The position and size
of the ship’s boats are based on the 1839 plans (Terror’s boat positions are
depicted in red ink), with slight modifications to accommodate the different
positions of deck fittings on HMS Terror.

Deck Placement and Wall Partitions:

The
1845 annotations (in green ink) of the 1836 Terror profile appear to contain
errors. Specifically, the placement of the decks match the 1845 stern
modification plans perfectly, but do not match the position of the decks in the
1836 inboard profile. However, the drawn position of the walls and deck
partitions of the 1845 modifications (in green ink) do match the 1836 and 1813 plans
precisely, or make logical accommodations for new equipment (e.g. the
locomotive). This would suggest that the 1845 annotations based on the stern
redesign were simply copied to the plans and not specifically adapted for HMS
Terror. Thus, in my plans the position the wall partitions correspond with the
1845 annotations and unmodified 1836 plans, but the position of the decks are depicted
as in the 1836 plans. The construction of the upper decks (doubling) corresponds
to the 1839 and 1836 inboard profiles.

Bulwarks:

All
the plans are inconsistent regarding the height of the Terror’s bulwarks. As
described in a previous post, the 1839 Inboard profile is obviously meant to
depict the Erebus (the bulwarks would be over ten feet high if placed in this
position on the Terror). The 1845 annotations (in green ink) on the 1836 inboard
profile likely reflect the proper position at the stern, but do not extend all
the way to the bow and appear to be drawn at an inappropriate angle (possibly
because it was directly copied from the 1845 stern modifications). To rectify
this issue, I traced the cap rail of the 1836 plans and then raised it into
position to match the stern location of the cap rail depicted in the 1845
modifications (in green ink). The bulwark lines were then extended at the bow
to intersect this new cap rail position. Interestingly, this new position
appears to match a pencil line marked on the plan of HMS Vesuvius. This,
combined with the annotations to the stempost, strongly suggests that the pencil
lines on HMS Vesuvius plans were meant to depict modifications to HMS
Terror. This makes some sense; by 1845 the 1836 Terror profile was so densely
annotated that that a new sheet may have been required (HMS Vesuvius was
identical to HMS Terror and HMS Beelzebub).

Rudder:

The
internal construction of the rudder is based on the 1836 profile, but its size,
shape, position, and hardware are based on the 1845 stern plans and the
corresponding annotations on the 1836 plans (in green ink).

Solid Chock Channels:

The
1836 plans for HMS Terror show a large gap, roughly amidships, in the solid
chock channels, and this is confirmed by contemporary paintings by Owen Stanley.
As described by Rice (Ross 1847a), in 1839 continuous solid chock channels were
constructed on both Erebus and Terror and are shown in the 1839 profiles and
deck plans representing both ships. All contemporary 1845 paintings/drawings of
the Terror depict solid chock channels surrounding the ship; therefore, a solid
chock channel consistent with the 1839 profile is utilized for my plans.

Mast Positions and Rake:

The mast
position and rake are based on the 1836 inboard profile (which, as described
previously, differs from the 1813 profile). Configurations of the mast steps
and their method of attachment are based on the 1813 plans (mizzenmast) and 1836
plans (foremast and mainmast), but the taper of the masts (not depicted in either
the 1813 of 1836 plans) is based on the 1839 plans.

Windows:

HMS Terror was originally designed with five stern
windows, and drawings by Own Stanley made during Back’s 1836 voyage indicate
that each had six panes.

However,
the central window was removed during the 1845 refit to make room for the new
propeller well and the new rudder position, a modification corroborated by the drawings
of Stanely, Gore, and others.

An
engraving of Franklin’s cabin published in 1845 by the Illustrated London News
shows that the windows each had four large panes (probably double-paned) with
very robust sills and muntins.Planks:

As the
1839 midships cross section indicates, the hull planks range in width from 8
inches on most areas of the hull to more than 10 inches (average) at the wales.
This is corroborated by the 1845 stern plan which depicts hull planking
averaging about 9 inches in width. However, it should be noted that the 1845 stern
plan displays that the planks were carefully spiled with no drop planks, so it
can be expected that plank widths would vary significantly beyond the average
width. In my plans of HMS Terror, all hull planks aim for an average width of ca.
9 inches. The wale planks have a maximum width of ca. 14 inches at the touch,
narrowing to ca. 7 inches at the butts. The wale planks are based on the hook
and butt design used for bomb vessels as depicted by Goodwin (1989), a planking
system which was also commonly used on polar exploration vessels and other
sturdy craft (Ware 1991).